Recently we have purchased an iPhone and iPod Touch external battery as a backup. It has been very handy when traveling, particularly during the long flights. Below is a summary of our research on the pros and cons of different iPhone battery extenders.
This is the charger we purchased. Even though it is on the expensive side, it worked great for us, providing at least 10+ extra hours of video and game time on our iPhone. Manufacturer claims 100 hours of music, 21 hours of video, or 6 hours of extra talk time.
Another advantage is that it actually charges your iPhone. This means that when your iPhone is charged, you can unplug the battery pack and share it with other iPhone, iPad, and iPod Touch users in your family. One disadvantage is that the iPhone charger is external and it does not attach to your device.
This iPhone battery pack is also one of the best in the market, recharges your iTouch or iPhone fully 2 times. If you have a family with more than one mobile device, you can share this external battery pack easily. Another nice feature is that when you are recharging your battery pack you can recharge your iPhone simultaneously. This is really useful when traveling. Fro example if you bring only one power cord along, you do not need to decide between recharging your phone versus recharging your battery pack.
Although this does not last as long as the other iPhone battery packs, the affordable price and the fact that you do not need to have a cable makes this battery pack attractive. It works with iPod nano, 1G, 2G, 3G, iPod classic 4G, 5G, 5.5G, 6G, iPod touch, iPhone and iPad.The manufacturer claims that this battery extender provides up to 30 hours of music playback, 6 hours of video playback and or 3 hours of talk. Good for short trips and occasional use.
This is one of the most expensive iPhone battery packs. However the convenience of the case form factor (no cables to deal with) may worth the price for some users. This charger doubles the battery life of your iPhone. One thing to note is that if you purchase a case-shaped iPhone battery, you will not be able to use it for iPod touch or iPad. Also if the next generation iPhones have different casing (as it is rumored) then when you upgrade your phone, the charger may become useless.